The invention relates to a spinning machine having a plurality of spinning units arranged in at least one row next to one another which each comprise devices for spinning a yarn and devices for winding up this yarn into a wound-up package. A movable arrangement for eliminating a yarn breakage is provided which can be applied to the individual spinning units and which comprises devices for the temporary taking-over of a newly spun yarn, devices for taking the broken yarn from the wound-up package, devices for connecting the newly spun yarn and the yarn taken off the wound-up package, devices for winding the connected yarn onto the wound-up package and devices for returning the wound-up package and the travelling yarn to the respective spinning unit. Devices belonging to the movable arrangement have a drive for winding up the yarn, this drive, while the devices for the storing of the yarn are emptied, being drivable at an increased winding speed.
In the case of a spinning machine of this type, as it is known on the basis of the German Patent Document DE-A 38 17 222, the yarn length deposited in the devices for storing the yarn can be determined relatively precisely because of the time which is required for establishing the yarn connection and during which the winding-up of the yarn does not take place. In contrast, it is very difficult to determine when the stored yarn length will be used up, that is, when the devices for the storing of the yarn are completely empty and the travelling yarn and the wound-up package may be returned to the spinning unit. Because of different parameters, a very different slippage may occur between the wound-up package and the devices for the winding-up so that it is not precisely determined which yarn length is wound up during which time and withdrawn from the devices for the storing. This may result in an overstraining of the yarn and imprecisions in the winding-up. This is true particularly since also before the yarn transfer to the spinning unit and the transfer of the wound-up package to the spinning unit, the excess yarn length should have been used up which was the result of the fact that the yarn, during the yarn connecting, is guided through the arrangement for eliminating a yarn breakage and in the process forms a so-called "yarn knee".
It is also known (German Patent Document DE-A 38 24 850) to equip each spinning unit with a yarn storage device in the form of a suction tube which is arranged between a pair of delivery rollers of the spinning unit and the area into which a splicing device of the movable arrangement is brought. The movable arrangement does not comprise any separate devices for the winding-up of the yarn after the establishment of the yarn connection. The yarn length stored in the stationary storage device must therefore, after the establishment of the spliced connection, be used up by a difference between the delivery speed at which the yarn is spun, and the wind-up speed at which the yarn is wound up during the normal operation.
It is also known (European Patent Document EP-A 0 277 717) to assign to each spinning unit a stationary yarn storage device which is operative during the normal spinning operation. In this construction, the yarn storage device is equipped with sensors which detect the loop size of the yarn disposed in the yarn storage device and which control the winding speed as a function of it.
In an older German Patent Application P 39 05 940.5 of the applicants corresponding in part to U.S. Pat. No. 5,079,908, which is no prior publication, a spinning machine of the initially mentioned type is described in which, additionally, a sensor is assigned to the devices for the storage of the yarn by means of which the point in time of the emptying can be determined. As a function of this determination, the winding speed of the devices of the movable arrangement for the winding-up is controlled.
It is an object of the invention to develop a spinning machine of the initially mentioned type such that, during and mainly after the establishment of a yarn connection, a controlled yarn travel is ensured at any time until the travelling yarn and the wound-up package have been returned to the spinning unit.
This object is achieved according to preferred embodiments of the invention in that a sensor which determines the point in time of the emptying is assigned to the devices for the storing of the yarn, this sensor being connected to a control device and the signal of which determines the starting point in time of a time period indicated in the control unit, during which the drive of the devices for the winding-up, which are part of the movable arrangement, still continues to run at an increased winding speed.
By means of this construction, it is possible to very precisely determine the yarn length wound up during the increased winding speed and to adapt it to the excess length to be used up. This excess length to be used up is composed of the yarn length deposited in the devices for storing the yarn and of the excess length obtained as a result of the deflection of the yarn travel in the arrangement in comparison to the yarn travel in the spinning unit Imprecisions during the emptying of the devices for the storage which occur particularly during the acceleration to the high wind speed, are eliminated completely. It will then be possible to completely or with a given part use up the excess length of the so-called "yarn knee".
In a further development of the invention, it is provided that the control device contains a control program which accelerates the drive of the devices for the winding up which belong to the movable arrangement, after the establishment of the yarn connection, first to a winding speed which amounts to approximately twice the winding speed of a spinning unit, and then reduces it to a lower winding speed which, however, is still above the winding speed of the spinning unit before the devices for the storing of the yarn have been emptied. As a result, it is achieved that, during the determined time period which is needed for the complete or partial using-up of the excess length caused by the "yarn knee", no major decelerations of the winding roller must take place which, under certain circumstances, may be connected with slippage phenomena and may therefore be the cause of inaccuracies.
In a further development of the invention, it is provided that the control program reduces the winding speed to an at least approximately constant value. As a result, it is possible to simplify the control device by the fact that only a time period is determined which is required for the complete or partial using-up of the excess length caused by the "yarn knee". The signal of the sensor, which may occur at different points in time, will take place when essentially the same winding speeds exist so that the time period for the continuation of the travelling at this increased winding speed may essentially be kept constant.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.